Since the early 70's, flue cured tobacco farmers have turned to bulk tobacco curing since it requires less labor and is generally more efficient than conventional stick curing. In bulk curing, the tobacco leaf material is packed in bulk and oriented within the curing and drying structure in such a manner that air can be circulated vertically through the mass of tobacco leaves. Typically, a forced air furnace system is utilized that acts to generate a system of air and continuously circulate the air through the tobacco. A curing and drying schedule is maintained during the curing and drying process and in so maintaining such a schedule it is necessary to add heat from time to time to the system of circulating air. This is typically accomplished by a furnace system such as an oil or gas fired furnace.
As mentioned above, the system of air is continuously circulated and generally this is accomplished by an electrically driven fan that may generally range between five and ten horsepower. Typically the curing and drying process will last approximately six to seven days and throughout this curing the fan is run continuously.
It is in this area of the air flow control that many problems have been experienced in bulk tobacco curing and drying structures. One such problem is where the electric motor driving the fan fails or where electricity to the motor is inadvertently interrupted. The ceasing of air flow within the structure results in the tobacco being severely damaged and inappropriate for marketing. This is especially a problem in bulk curing because the tobacco is tightly packed together and once air flow is stopped, the tobacco leaf material finds itself surrounded by warm or hot pockets of moisture and if this state is allowed to stand for an even small amount of time, the tobacco leaf material will rot and severe damage will be imparted to the tobacco crop material within the drying structure.
Therefore, there is a real need for the farmer to be appraised of the fact that air flow within a bulk tobacco curing and drying structure has ceased or falls below a preselected value in order that the farmer can take steps to rectify the problem and save the tobacco crop material from rotting or being damaged.